The present invention relates generally to a safety device for gas tubing, and more particularly to a thermally-sensitive safety device for gas tubing.
Although the modern families are well equipped with facilities of supplying gas, water, and electricity so as to provide the family life with convenience. However, the occurrence of accidents may be relatively increased. Therefore, as far as the facility of gas supply is concerned, overflow control valves will be installed on gas tubing in most of families to prevent gas leakage. The overflow control valve works like that when the gas tubing ruptures, the pressure difference generated by different flow speed of the gas drives a ball to block off a gas passage through which fluids flow, thereby the gas supply is stopped.
However, the aforementioned overflow control valve can automatically block off the gas passage to prevent the gas from explosion while the gas tubing ruptures, but the overflow control valve fails to detect the situation of the gas tubing on fire or ambient temperature being abnormally high. In other words, the overflow control valve is still not safe enough.
The primary objective of the present invention is to provide a thermally-sensitive safety device for gas tubing, automatically blocking off a gas passage to avoid accidental explosion while ambient temperature is abnormally high.
The secondary objective of the present invention is to provide a thermally-sensitive safety device for gas tubing, automatically blocking off a gas passage while the gas is overflowed.
The foregoing objectives of the present invention are attained by the thermally-sensitive safety device for the gas tubing, including a main body, a thermally-sensitive control valve and an overflow control valve. The main body is provided with an inlet, an outlet and a gas passage communicated with said inlet and said outlet. The thermally-sensitive control valve has a restraining member, a biasing unit, a thermally-sensitive member and a stopping unit. The restraining member is mounted in the gas passage adjacent to the inlet and has an admission aperture in communication with the inlet for enabling entry of gas into the gas passage. The biasing unit is mounted closely behind said restraining member and has an elastomer and a ball biased by said elastomer. The thermally-sensitive member is installed in the gas passage and has a receiving space for receiving a distal end of said restraining member, said elastomer and said ball, and a stopping portion disposed at a distal end thereof for stopping and keeping said ball in said receiving space in normal situation. The stopping unit is mounted in the gas passage behind said thermally-sensitive member and has a bushing with a through hole in alignment with said ball, and an oil seal installed in the through hole of the bushing. Wherein the through hole of the bushing has a larger inner diameter than said ball and said oil seal has a smaller inner diameter than said ball. Wherein said thermally-sensitive member melts while ambient temperature is higher than the melting point thereof, whereby said ball is biased by said elastomer to contact against the oil seal so as to seal the through hole of the bushing such that the gas passage is blocked off.